arXiv subjects

Qiao Shi

Publications and source records attributed to Qiao Shi.

4 recordsLinked to original sources

arXiv2026

Security in Low-Altitude ISAC with Coupled Communication and Sensing Information Leakage

Secure information transmission in integrated sensing and communication (ISAC) systems deployed in low-altitude wireless networks (LAWN) is particularly challenging due to the open airspace and the broadcast nature of wireless signals reused for both communication and sensing, which give rise to more severe and complex security threats. This paper investigates the joint communication and sensing security of low-altitude ISAC systems where a communication eavesdropper (CEve) cooperates with and assists a sensing eavesdropper (SEve), leading to coupled communication and sensing information leakage. We define a recoverable signal power ratio (RSR) that quantifies the degree of coupling between communication eavesdropping and sensing information leakage. Based on this coupling, we formulate a joint eavesdropping mutual information (MI) that facilitates unified analysis and optimization for the overall security. Subsequently, we design the transmit beamformer that maximizes the weighted sum of legitimate communication and sensing MI under the joint information-leakage constraint. Simulations show that the proposed scheme converges rapidly and effectively exploits the coupling between communication eavesdropping capability and sensing information leakage.

eess.SP↗

arXiv2025

Waveform and Filter Design for Integrated Sensing and Communication Against Signal-dependent Modulated Jamming

This paper focuses on an integrated sensing and communication (ISAC) system in the presence of signal-dependent modulated jamming (SDMJ). Our goal is to suppress jamming while carrying out simultaneous communications and sensing. We minimize the integrated sidelobe level (ISL) of the mismatch filter output for the transmitted waveform and the integrated level (IL) of the mismatch filter output for the jamming, under the constraints of the loss in-processing gain (LPG) and the peak-to-average power ratio (PAPR) of the transmitted waveform. Meanwhile, the similarity constraint is introduced for information-bearing transmit waveform. We develop a decoupled majorization minimization (DMM) algorithm to solve the proposed multi-constrained optimization problem. In contrast to the existing approaches, the proposed algorithm transforms the difficult optimization problem involving two variables into two parallel sub-problems with one variable, thus significantly speeding up the convergence rate. Furthermore, fast Fourier transform (FFT) is introduced to compute the closed-form solution of each sub-problem, giving rise to a greatly reduced computation complexity. Simulation results demonstrate the capabilities of the proposed ISAC system which strikes a proper trade-off among sensing and jamming suppression.

eess.SP↗

arXiv2025

Joint Beamforming Design for Integrated Sensing and Communication Systems with Hybrid-Colluding Eavesdroppers

In this paper, we consider the physical layer security (PLS) problem for integrated sensing and communication (ISAC) systems in the presence of hybrid-colluding eavesdroppers, where an active eavesdropper (AE) and a passive eavesdropper (PE) collude to intercept the confidential information. To ensure the accuracy of sensing while preventing the eavesdropping, a base station transmits a signal consisting of information symbols and sensing waveform, in which the sensing waveform can be also used as artificial noise to interfere with eavesdroppers. Under this setup, we propose an alternating optimization-based two stage scheme (AO-TSS) for improving the sensing and communication performance. In the first stage, based on the assumptions that the perfect channel state information (CSI) of the AE and statistical CSI of the PE are known, the communication and sensing beamforming problem is formulated with the objective of minimizing the weighted sum of the beampattern matching mean squared error (MSE) and cross-correlation, subject to the secure transmission constraint. To tackle the non-convexity, we propose a semi-definite relaxation (SDR) algorithm and a reduced-complexity zero-forcing (ZF) algorithm. Then, the scenarios are further extended to more general cases with imperfect AE CSI and unknown PE CSI. To further improve the communication performance, the second-stage problem is developed to optimize the secrecy rate threshold under the radar performance constraint. Finally, numerical results demonstrate the superiority of the proposed scheme in terms of sensing and secure communication.

eess.SY↗

arXiv2020

Tensile properties of structural I clathrate hydrates:Role of guest-host hydrogen bonding ability

Clathrate hydrates (CHs) are one of the most promising molecular structures in applications of gas capture and storage, and gas separations. Fundamental knowledge of mechanical characteristics of CHs is of crucial importance for assessing gas storage and separations at cold conditions, as well as understanding their stability and formation mechanisms. Here, the tensile mechanical properties of structural I CHs encapsulating a variety of guest species (methane, ammonia, sulfureted hydrogen, formaldehyde, methanol, and methyl mercaptan) that have different abilities to form hydrogen (H-) bonds with water molecule are explored by classical molecular dynamics (MD) simulations. All investigated CHs are structurally stable clathrate structures. Basic mechanical properties of CHs including tensile limit and Young's modulus are dominated by the H-bonding ability of host-guest molecules and the guest molecular polarity. CHs containing small methane, formaldehyde and sulfureted hydrogen guest molecules that possess weak H-bonding ability are mechanically robust clathrate structures and mechanically destabilized via brittle failure on the (1 0 1) plane. However, those entrapping methyl mercaptan, methanol, and ammonia that have strong H-bonding ability are mechanically weak molecular structures and mechanically destabilized through ductile failure as a result of gradual global dissociation of clathrate cages.

physics.comp-ph↗